An electrical switch of the miniature type, such as a keyboard switch, for example, may comprise a dielectric housing having therein a movable contact member disposed in spaced relationship with a fixed contact member. The movable and the fixed contact members may be connected to respective electrical terminals which protrude outwardly of the housing for connection to respective portions of an electrical circuit, such as a digital pulse detector circuit, for example. Thus, depression of a typewriter-like key attached to the movable contact member causes it to move into momentary electrical engagement with the fixed contact member and produce a corresponding electrical pulse which is detected by the connected circuit.
In practice, it may be found that sudden release of the typewriter-like key and resulting movement of the movable contact member out of electrical engagement with the fixed contact member causes an undesirable vibration of the movable contact member. As a result, the movable contact member may again contact the fixed contact member, a condition generally referred to as "contact bounce", which produces a spurious electrical pulse. This spurious electrical pulse may be detected by the connected circuit as a sequential depression of the typewriter-like key to produce an intentional electrical pulse. Consequently, erroneous electrical data will be delivered to the connected circuit and may cause connected electrical equipment to function erratically.
Attempts have been made in the prior art to correct the problem of "contact bounce" by providing an electrical switch with a dielectric member which is disposed between the contact members of the switch in the "open" condition. However, in these prior art switches, the dielectric member generally is forced between the contact members to open the switch and to maintain the contact members in insulated spaced relationship with one another. Consequently, when the dielectric member is forced between the contact members, the resulting forceful rubbing engagement may cause excessive wear and possibly breakdown of the dielectric member. Furthermore, when the dielectric member is forcefully removed from between the contact members to permit the switch to close, the resulting rubbing of the dielectric member adds to the excessive wearing away and possibility of breakdown of the dielectric member.